This invention relates to microfilm card duplicating machines in which image copying of master card photographic images onto duplicate cards is effected.
Microfilm card duplicating machines accept master cards containing photographic images and also copy cards containing photo sensitive pieces of film of approximately the same size as the master image. By means of exposing and developing devices built into the machines the images from the master cards are duplicated on to the copy cards as required. In many instances the master cards also contain punched card information relating for example to a numerical designation or other classification in the form of punched holes. Frequently it is necessary to duplicate both the microfilm image and the punched holes.
The duplication of the two types of information can be achieved in one of four alternative ways:
1. Unexposed copy cards can be prepunched in separate punching equipment as required and to correspond to the punched data on respective master cards to be duplicated. The punched copy cards are then fed through a microfilm card duplicating machine in sequence with their respective master card to reproduce the microfilm image onto the copy cards. Providing that the sequence of master and copy cards and the quantities of copy cards per master is correct, each master card image will be duplicated only on to copy cards having the same holes as the master. This is achieved by carefully keeping the decks of copy cards and master cards in exactly the right order. A misplacement of just one master or copy card would cause some or all duplicate copies from that point on in the production run to have film images and punched holes imcompatible to each other. Although this method is most commonly used, there is high risk of error and visual checking of copy card decks before distribution is often necessary.
To overcome this problem verifying units have been made that compare the holes in master and copy cards just prior to the imaging exposure and stop the copying process in the event of a mismatch. The incorporation of this comparator device increases considerably the cost of the duplicator particularly where complex punch coded information is to be accommodated.
2. Unpunched copy cards are exposed in the microfilm card duplicator so that the micro image is transferred to a required number of copy cards for each master card. The copy cards are then stacked in sequence and the master cards separately stacked in the same sequence. The stack of unpunched copy cards and the stack of master cards which are punched are transferred to a key punch machine. This machine can be operated either manually by reading the information from the punched master or, semi-automatically, by feeding the master manually into an automatic copying punch at the appropriate time. Either way the copy cards are punched in the machine with the same information as the masters.
This method is very difficult to control because it is difficult to know which microfilm image is on which card without constantly looking at the cards in a reader which projects the image back to readable size. This method is not used frequently.
3. The images from the master cards are first reproduced onto unpunched copy cards and then the master cards and copy cards are manually interleaved so that each master card is followed by the unpunched copy cards containing the image of that particular master. These interleaved decks are then transferred to a key punch machine such as an IBM 029, which is operated in a semi-automatic mode whereby it reproduces each master on to its succeeding copy cards. Here again any human error in arranging the interleaved deck can cause significant errors and the manual labour involved in arranging interleaved decks is not always acceptable.
4. Another method of obtaining punched data and film image data accurately duplicated is to use a card duplicating machine that punches the copy data in at the same time as the image is transferred. This is traditionally the most reliable method but Card reproducers which do this are extremely expensive. Many card users who have card duplicating requirements of such a volume that the above problems are of concern to them, already have conventional reproducing punch machines that they use to punch their master cards. To purchase an additional machine that contains image duplication with punch hole duplication would duplicate unnecessarily the punching facility.